In many internal combustion engine applications a pressure regulator is required for use together with the fuel pump.
Among the situations wherein such regulators are required are high performance engines such as are used in racing. Such engines require a greater volume of fuel on demand than corresponding engines use for more normal applications. To provide this greater volume, a higher output pressure fuel pump must be used. Unfortunately, these higher pressure fuel pumps often operate at pressures which will overcome the check or needle valve in the carburetor and flood the engine. That is the background reason why pressure regulators such as the present invention are required.
More specifically, a fuel pump regulator is required because as the volume of fuel handled increases and the cross-sectional area in the fuel lines, of course, stays the same, the pressure must increase in order to accommodate the greater flow of fuel. As stated above, this increase in pressure, if not regulated and stepped down, will overcome the check or needle valve in the carburetor, thus completely frustrating the fuel checking action in the carburetor, and forcing fuel past the check or needle valve of the carburetor and into the carburetor at a time when no fuel is intended to be entering the carburetor, thus resulting in engine flooding.
The free flow, open throttle, pressure of a typical high performance fuel pump is often on the order of 3 psi. The shut-off pressure at the carburetor in this example situation is often on the order of 7 psi. Thus, when the engine is working at open throttle, with the pump at full capacity, there is no need for pressure regulation. The need arises as the pressure builds when the carburetor decreases or shuts-off demand, as it does at engine idle, deceleration or other routine circumstances during normal operation of internal combustion engines. On such occasions, the fuel pressure can climb to a point at which it overcomes the carburetor needle valve and floods the engine. The pressure regulator controls the action of the fuel pump in such situations in order to achieve proper and normal operation of the engine.